Related fields include evaluation and screening of candidate materials and processes for thin-film stacks and devices.
The performance of advanced thin-film devices is often sensitive to thickness of individual layers. Tolerances on average film thickness, thickness uniformity, and continuity of coverage (i.e., absence of “pinholes,” cracks, or other gaps in the layer that constitute “coverage defects”) may accordingly be very tight. Measurement of these parameters, including real-time monitoring during fabrication processes, can be challenging. In particular, visual evaluation of coverage defects can be time-consuming and prone to errors.
When selecting materials and processes for new or improved devices, coverage properties are often a critical factor. Therefore, a need exists for a rapid, reliable analysis method for coverage defects in candidate films.
When removing material from a device being fabricated (e.g., by etching), a particular thickness of a specific material may need to be left in place. Therefore, a need exists for a reliable method of monitoring the composition and thickness of the topmost layers in a device film stack.